Should I use this flag for Cromwell's Ironsides?
From this site:
http://wiki.bcw-project.org/parliamentarian/horse-regiments/oliver-cromwell'A number of cornets belonging to officers of Cromwell's regiment were recorded. The fields of these flags are of different colours, red, yellow, blue and white. While the ideal was for all troops of the same regiment to carry cornets with the same field colour, this was not strictly adhered to in the army of the Eastern Association, as Manchester's horse also carried cornets of different colours. It is also possible that some of the recorded cornets relate to officers' service prior to or after leaving Cromwell's regiment.
Colonel Oliver Cromwell's cornet design is unknown. In a contemporary manuscript of flag illustrations it is left blank, implying either that it was plain white, or that the illustrator didn't get around to completing it. A plain white cornet is plausible, as Cromwell's favoured colour when later commanding the army in Ireland was white (whether this refers to infantry or cavalry flags or sashes is unclear, but Cromwell was painted wearing a white sash). Additionally, colonels and more senior officers often chose a plain design for their own troop's cornet, sometimes made of patterned fabric (for example Sir Thomas Fairfax and Lord Grey of Wark). Therefore a white cornet is the most likely candidate for Cromwell's troop but this is in no way definite. There is no contemporary evidence for the troop carrying a black flag with white lion derived from Cromwell's coat of arms, which is a modern 'reconstruction'.
Captain Henry Ireton's cornet was red with a red and white fringe and a complicated white scroll PRO (used for both lines) DIVINIS QUI AMITTIT SERVAT and HUMANIS VIM VI).
Captain James Berry's cornet was red with a red and yellow fringe with a diagonal motto in white with no scroll Pro Rege et Lege Parati).
Captain Samuel Porter's cornet was yellow with a yellow and white fringe featuring an arm wielding a sword emerging from a cloud (all proper) and a four-part scroll with the motto PRO FIDE SEMEL TRADITA).
Captain John Grove's cornet was white with a white fringe, showing an armoured arm weilding a sword (proper) and a three-part scroll FOR TRVETH AND PEACE).'
The flag in the above picture is his standard as Lord Protector if my memory serves me right and was not used till well after the Civil War, certainly no earlier than the execution of the King. I have seen some Parliamentarian re-enactors use this standard although again it wasn't the official flag till 1649:
https://en.wikipedia.org/wiki/Flags_of_the_English_Interregnum#/media/File:Flag_of_the_Commonwealth_(1649-1651).svg